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authorAlexander Potapenko <glider@google.com>2016-03-25 14:21:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-25 16:37:42 -0700
commit7ed2f9e663854db313f177a511145630e398b402 (patch)
treef9dfba81a688864a4d78689470f624b0a482f545 /mm/kasan
parente6e8379c876de16c6b78f83b15d5ac32c79cb440 (diff)
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mm, kasan: SLAB support
Add KASAN hooks to SLAB allocator. This patch is based on the "mm: kasan: unified support for SLUB and SLAB allocators" patch originally prepared by Dmitry Chernenkov. Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrey Konovalov <adech.fo@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kasan')
-rw-r--r--mm/kasan/kasan.c102
-rw-r--r--mm/kasan/kasan.h34
-rw-r--r--mm/kasan/report.c54
3 files changed, 179 insertions, 11 deletions
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 1ad20ade8c91..7c82509ef169 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -334,6 +334,59 @@ void kasan_free_pages(struct page *page, unsigned int order)
KASAN_FREE_PAGE);
}
+#ifdef CONFIG_SLAB
+/*
+ * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
+ * For larger allocations larger redzones are used.
+ */
+static size_t optimal_redzone(size_t object_size)
+{
+ int rz =
+ object_size <= 64 - 16 ? 16 :
+ object_size <= 128 - 32 ? 32 :
+ object_size <= 512 - 64 ? 64 :
+ object_size <= 4096 - 128 ? 128 :
+ object_size <= (1 << 14) - 256 ? 256 :
+ object_size <= (1 << 15) - 512 ? 512 :
+ object_size <= (1 << 16) - 1024 ? 1024 : 2048;
+ return rz;
+}
+
+void kasan_cache_create(struct kmem_cache *cache, size_t *size,
+ unsigned long *flags)
+{
+ int redzone_adjust;
+ /* Make sure the adjusted size is still less than
+ * KMALLOC_MAX_CACHE_SIZE.
+ * TODO: this check is only useful for SLAB, but not SLUB. We'll need
+ * to skip it for SLUB when it starts using kasan_cache_create().
+ */
+ if (*size > KMALLOC_MAX_CACHE_SIZE -
+ sizeof(struct kasan_alloc_meta) -
+ sizeof(struct kasan_free_meta))
+ return;
+ *flags |= SLAB_KASAN;
+ /* Add alloc meta. */
+ cache->kasan_info.alloc_meta_offset = *size;
+ *size += sizeof(struct kasan_alloc_meta);
+
+ /* Add free meta. */
+ if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
+ cache->object_size < sizeof(struct kasan_free_meta)) {
+ cache->kasan_info.free_meta_offset = *size;
+ *size += sizeof(struct kasan_free_meta);
+ }
+ redzone_adjust = optimal_redzone(cache->object_size) -
+ (*size - cache->object_size);
+ if (redzone_adjust > 0)
+ *size += redzone_adjust;
+ *size = min(KMALLOC_MAX_CACHE_SIZE,
+ max(*size,
+ cache->object_size +
+ optimal_redzone(cache->object_size)));
+}
+#endif
+
void kasan_poison_slab(struct page *page)
{
kasan_poison_shadow(page_address(page),
@@ -351,8 +404,36 @@ void kasan_poison_object_data(struct kmem_cache *cache, void *object)
kasan_poison_shadow(object,
round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
KASAN_KMALLOC_REDZONE);
+#ifdef CONFIG_SLAB
+ if (cache->flags & SLAB_KASAN) {
+ struct kasan_alloc_meta *alloc_info =
+ get_alloc_info(cache, object);
+ alloc_info->state = KASAN_STATE_INIT;
+ }
+#endif
+}
+
+static inline void set_track(struct kasan_track *track)
+{
+ track->cpu = raw_smp_processor_id();
+ track->pid = current->pid;
+ track->when = jiffies;
}
+#ifdef CONFIG_SLAB
+struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
+ const void *object)
+{
+ return (void *)object + cache->kasan_info.alloc_meta_offset;
+}
+
+struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
+ const void *object)
+{
+ return (void *)object + cache->kasan_info.free_meta_offset;
+}
+#endif
+
void kasan_slab_alloc(struct kmem_cache *cache, void *object)
{
kasan_kmalloc(cache, object, cache->object_size);
@@ -367,6 +448,17 @@ void kasan_slab_free(struct kmem_cache *cache, void *object)
if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
return;
+#ifdef CONFIG_SLAB
+ if (cache->flags & SLAB_KASAN) {
+ struct kasan_free_meta *free_info =
+ get_free_info(cache, object);
+ struct kasan_alloc_meta *alloc_info =
+ get_alloc_info(cache, object);
+ alloc_info->state = KASAN_STATE_FREE;
+ set_track(&free_info->track);
+ }
+#endif
+
kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
}
@@ -386,6 +478,16 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
kasan_unpoison_shadow(object, size);
kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
KASAN_KMALLOC_REDZONE);
+#ifdef CONFIG_SLAB
+ if (cache->flags & SLAB_KASAN) {
+ struct kasan_alloc_meta *alloc_info =
+ get_alloc_info(cache, object);
+
+ alloc_info->state = KASAN_STATE_ALLOC;
+ alloc_info->alloc_size = size;
+ set_track(&alloc_info->track);
+ }
+#endif
}
EXPORT_SYMBOL(kasan_kmalloc);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 4f6c62e5c21e..7b9e4ab9b66b 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -54,6 +54,40 @@ struct kasan_global {
#endif
};
+/**
+ * Structures to keep alloc and free tracks *
+ */
+
+enum kasan_state {
+ KASAN_STATE_INIT,
+ KASAN_STATE_ALLOC,
+ KASAN_STATE_FREE
+};
+
+struct kasan_track {
+ u64 cpu : 6; /* for NR_CPUS = 64 */
+ u64 pid : 16; /* 65536 processes */
+ u64 when : 42; /* ~140 years */
+};
+
+struct kasan_alloc_meta {
+ u32 state : 2; /* enum kasan_state */
+ u32 alloc_size : 30;
+ struct kasan_track track;
+};
+
+struct kasan_free_meta {
+ /* Allocator freelist pointer, unused by KASAN. */
+ void **freelist;
+ struct kasan_track track;
+};
+
+struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
+ const void *object);
+struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
+ const void *object);
+
+
static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
{
return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 745aa8f36028..3e3385cc97ac 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -115,6 +115,46 @@ static inline bool init_task_stack_addr(const void *addr)
sizeof(init_thread_union.stack));
}
+#ifdef CONFIG_SLAB
+static void print_track(struct kasan_track *track)
+{
+ pr_err("PID = %u, CPU = %u, timestamp = %lu\n", track->pid,
+ track->cpu, (unsigned long)track->when);
+}
+
+static void object_err(struct kmem_cache *cache, struct page *page,
+ void *object, char *unused_reason)
+{
+ struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
+ struct kasan_free_meta *free_info;
+
+ dump_stack();
+ pr_err("Object at %p, in cache %s\n", object, cache->name);
+ if (!(cache->flags & SLAB_KASAN))
+ return;
+ switch (alloc_info->state) {
+ case KASAN_STATE_INIT:
+ pr_err("Object not allocated yet\n");
+ break;
+ case KASAN_STATE_ALLOC:
+ pr_err("Object allocated with size %u bytes.\n",
+ alloc_info->alloc_size);
+ pr_err("Allocation:\n");
+ print_track(&alloc_info->track);
+ break;
+ case KASAN_STATE_FREE:
+ pr_err("Object freed, allocated with size %u bytes\n",
+ alloc_info->alloc_size);
+ free_info = get_free_info(cache, object);
+ pr_err("Allocation:\n");
+ print_track(&alloc_info->track);
+ pr_err("Deallocation:\n");
+ print_track(&free_info->track);
+ break;
+ }
+}
+#endif
+
static void print_address_description(struct kasan_access_info *info)
{
const void *addr = info->access_addr;
@@ -126,17 +166,10 @@ static void print_address_description(struct kasan_access_info *info)
if (PageSlab(page)) {
void *object;
struct kmem_cache *cache = page->slab_cache;
- void *last_object;
-
- object = virt_to_obj(cache, page_address(page), addr);
- last_object = page_address(page) +
- page->objects * cache->size;
-
- if (unlikely(object > last_object))
- object = last_object; /* we hit into padding */
-
+ object = nearest_obj(cache, page,
+ (void *)info->access_addr);
object_err(cache, page, object,
- "kasan: bad access detected");
+ "kasan: bad access detected");
return;
}
dump_page(page, "kasan: bad access detected");
@@ -146,7 +179,6 @@ static void print_address_description(struct kasan_access_info *info)
if (!init_task_stack_addr(addr))
pr_err("Address belongs to variable %pS\n", addr);
}
-
dump_stack();
}